package Lee_code;

public class Lee_96 {
    public int numTrees(int n)
    {
        int[] dp = new int[n+1];
        //零也是1
        dp[0] = 1;
        dp[1] = 1;
        dp[2] = 2;

        for(int i=3; i<=n; i++)
        {
            for(int j=1; j<=i; j++)
            {
                dp[i] = dp[j-1]*dp[i-j];
            }
        }
        return dp[n];
    }
}
